Why carrier coverage maps can be wrong

Short answer

Carrier and FCC mobile coverage maps are computer-modeled estimates of outdoor signal, not measurements of what you’ll get inside your home. Real-world results vary with terrain, buildings, foliage, your specific phone, and congestion, so maps tend to look more optimistic than reality. The only reliable test is trying the network where you actually spend time.

What “modeled coverage” means

Carriers estimate coverage by modeling signal propagation from their towers, then publish the result as a map. It’s a prediction, not a survey of your living room. The modeled nature is why two people standing in the same “covered” spot can have very different experiences.

Why your reality differs

Buildings. Walls, metal, and low-E glass cut signal — especially higher-frequency 5G.
Terrain & foliage. Hills and trees block or weaken signal.
Bands. A map may count low-band coverage that’s weak indoors as “covered.”
Your device. Older phones support fewer bands and have weaker antennas.
Congestion. A busy tower slows everyone, and may deprioritize MVNO traffic.

How to get the truth

Compare each carrier’s map for your home, work, and commute — note mid-band vs low-band 5G.
Cross-check independent, crowdsourced coverage maps for a reality check.
Test the network yourself with a trial or cheap prepaid/MVNO SIM before switching.
If indoor signal is the problem, look at Wi-Fi calling or a signal booster.

Frequently asked questions

Why does my phone have no signal where the map shows coverage?

Coverage maps predict outdoor signal using models, not measurements inside buildings. Walls, terrain, foliage, your specific phone, and network congestion can all reduce real-world signal below what the map suggests.

How can I really tell if a carrier works where I live?

Test it. Use a free trial, an eSIM trial, or a cheap prepaid/MVNO SIM on that network for a week at home, work, and along your commute. Real-world testing beats any map.